International Mother Language Day is a worldwide annual observance held on 21 February to promote awareness of linguistic and cultural diversity and to promote multilingualism. First announced by UNESCO on 17 November 1999, it was formally recognized by the United Nations General Assembly.

In Bangladesh, 21 February 1952 is the anniversary of the day when the Bengalis of the then-Pakistani province of East Bengal (which is now the independent state of Bangladesh) fought for recognition of their Bengali language as Official Central State Languages instead of Provincial Language.